This invention relates generally to livestock feed compositions and more particularly to a feed composition designed to avert grass tetany in livestock. The feed composition is a stable solution of magnesium salts completely dissolved in a liquid energy source. The liquid feed supplement may be made available to the animals in appropriately located lick wheel feeders or other convenient liquid feed dispensing devices.
Grass tetany, also known as grass staggers, wheat pasture poisoning and downer syndrome, has long been a problem of magnitude in grass-fed cattle, sheep, goats, horses, and swine. Nutritional tetany is a useful, correct term for several disorders in livestock which are characterized by hypomagnesemia. Hypomagnesemia results in tonic and clonic muscular contractions and sudden death of the animal. Fibrillary twitchings of the muscles are followed by either a sustained contraction of muscles or jerking muscular contractions. The cardiac muscle also displays hyperirritability. Breathing becomes rapid and noisy, salivation may occur; and death follows either through spasm of the thoracic or cardiac muscles, or both.
Livestock grazing rapidly growing grasses are highly susceptible to grass tetany. Such grasses are usually low in magnesium and low in available carbohydrates; sucrose, fructose, glucose and other hexoses; but high in potassium.
The cause of tetany is not completely understood. Studies have indicated conflicting reports on the nutritional status of the affected animals. Aside from the deficiency of magnesium it has been suggested that other factors contribute to the disorder. Among these factors are low intakes of soluble carbohydrates, energy or dry matter; and high intakes of non-protein nitrogen, potassium, and transaconitate. Further, low levels of manganese, cobalt, phosphorus, sulfate, citrate and possibly other trace minerals contribute to the disorder.
It is well known that the onset of grass tetany in grass fed animals is due to a sudden fall in the level of magnesium ions in the blood stream; hence, the name hypomagnesemia. Although many factors are thought to contribute to the onset of tetany, the control of magnesium metabolism appears to be the primary issue. Hypomagnesemia is the first sign of the metabolic disorder and the whole problem can be eliminated by providing high levels of dietary megnesium which obviates the need for homostatic control.
To avert tetany in grass fed cattle, sheep, goats, horses, and swine, the animals must consume sufficient amounts of magnesium to maintain 2 to 3 milligrams of magnesium per 100 milliliters of blood serum. Attempts have been made to provide the necessary magnesium to grazing animals via magnesium compounds fed as loose minerals; or magnesium compounds mixed with solid feedstuffs, mixed with the drinking water, incorporated in salt blocks, and mixed with molasses.
Feeding magnesium compounds as loose minerals has not proved successful in averting tetany. Although feeding magnesium compounds in this manner can reduce the incidence of grass tetany, animals will not voluntarily consume sufficient amounts to alleviate the symptoms of hypomagnesemia. It has been suggested that animals refuse the magnesium compounds since they are highly unpalatable. Magnesium carbonate and magnesium oxide are only slightly soluble in saliva and do not readily ionize so that the animal is unable to detect the presence of magnesium. Magnesium acetate, magnesium chloride, and magnesium sulfate are hygroscopic, become solutions which either intermingle with other mineral components or leak from their container. Since these compounds are unstable, they are unsatisfactory.
In order to overcome the problems associated with feeding magnesium compounds as loose minerals, magnesium compounds have been admixed with solid feedstuffs, such as corn. This approach has also proved unsatisfactory for various reasons.
Due to the difference in the particle size of the magnesium compounds and the solid feed, there is a segregation of materials. Since a homogenous mixture cannot be maintained, some portions of the feed are rich in magnesium while other portions are deficient. Thus, the animals intake of needed magnesium in unpredictable.
Further, admixing magnesium with solid feed is costly both in terms of needed labor and in terms of material costs. High labor costs result due to the necessity of daily hand feeding, making this approach unfeasible under range conditions. Also, it is felt that the animals' consumption of the mixture is dictated by the desire for the solid feedstuff, such as corn rather than their need for magnesium.
Common practice has been to mix magnesium oxide in grain and transport sufficient quantities of the mixture to grazing animals daily when, in the mind of the feeder, grass tetany became imminent, or when one or more of the animals have succumbed. This practice is costly in terms of the grain and labor used; and justification for these high costs is based on either speculation as to the need, or a desperate attempt to minimize losses. It has become obvious that a more systematic, manageable approach is needed.
Attempts to incorporate magnesium compounds into block form, generally with salt, have met with little success. The problems associated with feeding loose minerals also apply to this approach. Either the block is unpalatable, unstable, or the block is consumed based on the animals' desire for a component other than magnesium.
Addition of magnesium compounds to the animal's drinking water has met with some success in averting tetany. However, this approach requires that the animals have access only to the treated water, a requirement that is often unfeasible under range conditions. Further, it has been observed that the compounds precipitate from solution under range conditions and become unavailable to the animals.
Feeding of a mixture of magnesium compounds and molasses has been known for some time. This method is not practical, however, since molasses is a product of commerce which varies widely, frequently being very high in potassium. Potassium, when fed with grasses also high in potassium, contributes to grass tetany since it restricts the absorption of magnesium into the blood stream.
Further, it has been demonstrated that the intake of the molasses mixture is controlled by the animals' desire for molasses. In U.S. Pat. No. 3,794,740, Achorn uses an overfeeding preventative such as ammonium sulfate or sodium chloride in a molasses containing feed supplement, which acts as a governor on the animals' appetite. (It should be noted, however, that ammonium per se, being alkaline, slows the absorption of magnesium into the blood stream).
While molasses is sometimes considered an energy source, the contained disaccharide must be inverted before it is available for absorption by the blood stream. The sucrose contained in the molasses must be digested in the alimentary canal, or inverted, to produce glucose and fructose before it can be absorbed into the blood stream where energy yielding compounds are needed. The low energy condition, thought to be a factor in tetany, is, therefore, not immediately overcome by the ingestion of molasses. Due to the time lag associated with digestion, molasses does not provide a readily available energy source.
Those concerned with the control of grass tetany and other magnesium dificiency related conditions recognize that the existing methods of control are inadequate.